Water-mediated structuring of bone apatite

International audienceIt is well known that organic molecules from the vertebrate extracellular matrix of calcifying tissues are essential in structuring the apatite mineral. Here, we show that water also plays a structuring role. By using solid-state nuclear magnetic resonance, wide-angle X-ray scattering and cryogenic transmission electron microscopy to characterize the structure and organization of crystalline and biomimetic apatite nanoparticles as well as intact bone samples, we demonstrate that water orients apatite crystals through an amorphous calcium phosphate-like layer that coats the crystalline core of bone apatite. This disordered layer is reminiscent of those found around the crystalline core of calcified biominerals in various natural composite materials in vivo. This work provides an extended local model of bone biomineralization

SYNTHESE ET ETUDE PAR RMN MULTINUCLEAIRE A L'ETAT SOLIDE DE CLUSTERS AL-O-P, MODELES D'UNITES DE CONSTRUCTION SECONDAIRES DE MATERIAUX MICROPOREUX

PARIS-BIUSJ-Physique recherche (751052113) / SudocCentre Technique Livre Ens. Sup. (774682301) / SudocSudocFranceF

Key Parameters Governing the Reversibility of Si/Carbon/CMC Electrodes for Li-Ion Batteries

International audienc

Bone mineral: new insights into its chemical composition

International audienceSome compositional and structural features of mature bone mineral particles remain unclear. They have been described as calcium-deficient and hydroxyl-deficient carbonated hydroxyapatite particles in which a fraction of the po 4 3− lattice sites are occupied by HPO 4 2− ions. The time has come to revise this description since it has now been proven that the surface of mature bone mineral particles is not in the form of hydroxyapatite but rather in the form of hydrated amorphous calcium phosphate. Using a combination of dedicated solid-state nuclear magnetic resonance techniques, the hydrogen-bearing species present in bone mineral and especially the HPO 4 2− ions were closely scrutinized. We show that these HPO 4 2− ions are concentrated at the surface of bone mineral particles in the so-called amorphous surface layer whose thickness was estimated here to be about 0.8 nm for a 4-nm thick particle. We also show that their molar proportion is much higher than previously estimated since they stand for about half of the overall amount of inorganic phosphate ions that compose bone mineral. As such, the mineral-mineral and mineral-biomolecule interfaces in bone tissue must be driven by metastable hydrated amorphous environments rich in HPO 4 2− ions rather than by stable crystalline environments of hydroxyapatite structure

First principles calculations of NMR parameters in biocompatible materials science: The case study of calcium phosphates, beta- and gamma-Ca(PO3)(2). combination with MAS-J experiments

First principles calculations of NMR parameters in biocompatible materials science: The case study of calcium phosphates, beta- and gamma-Ca(PO3)(2). combination with MAS-J experiment

Lipid-based nanostructured composite materials as Drug Delivery Systems

International audienceDes systèmes composites nanostructurées aux fonctionnalités originales ont été préparés en associant du matériel inorganique à des phospholipides ou des lipides

Solid-state NMR characterization of drug-model molecules encapsulated in MCM-41 silica

International audienceIn this contribution, we present a solid-state NMR approach to characterize drugmodel molecules as ibuprofen, benzoic acid, and lauric acid, encapsulated in MCM-41 silica and submitted to strong confinement effects. In particular, we show that by a careful choice of the solid-state NMR sequences, it is possible to efficiently characterize these highly mobile molecules and their interactions with the pore surface. Thus, we demonstrate that 13C NMR spectroscopy is a powerful tool to characterize and even quantify entrapped and non-entrapped species by using either single-pulse excitation (SPE) or cross-polarization (CP). Whereas the standard {1H}-13C CP experiment is of poor efficiency for mobile species, we show that 13C signal-to-noise (S/N) ratio can be significantly improved through 1H-13C cross-relaxation (namely, nuclear Overhauser effect, nOe) by using a 1H power-gated technique. The long transversal relaxation times [T2(1H) up to 22 ms] observed allow the setup of J-coupling-based experiments such as 2D {1H}-13C heteronuclear multiple-quantum coherence (HMQC) in order to fully characterize the encapsulated molecules. Thus, we demonstrate that the use of sequences derived from solution-state NMR such as these two latter experiments is highly efficient to characterize highly mobile organic molecules trapped in mesopores. Finally, we show that 1H spin diffusion-based experiments can give useful information on the proximities between trapped molecules and the silica surfac